While onstage at an AllThingsD conference in New York, Koum also announced that WhatsApp now sees an average of 8 billion inbound and 12 million outbound messages per day.

While WhatsApp and Twitter are very different platforms, the comparison does provide possible support for recent theories that younger users are turning to newer apps (like WhatsApp), while older social networking sites (Facebook, Twitter) are falling out of favor with this demographic.

Previously free, WhatsApp is now charging $0.99 per year – a change that has not yet caused “any drop off in user numbers or engagement,”reports TechCrunch.